This invention relates to improved safety valves for closing off the flow of production fluid upwardly through a well in the event of failure of some of the well equipment.
In a producing well, it is highly desirable to provide some type of safety mechanism for closing off the flow of production fluid upwardly through the well and to the surface of the earth in the event of a rupture or leak in one of the lines conducting that fluid, or in the event of any other type of derangement which might release oil into the surrounding area in uncontrolled fashion. This is particularly true, for example, in the case of wells drilled under a body of water, in which case the escape of even small amounts of oil from the well may very seriously pollute the water. There have in the past been devised various types of safety valves for closing off the flow of production fluid from a well, but all of these prior safety valves of which we are aware are either relatively difficult to position in the well or to operate, or are not as positive as would be desired in closing off the fluid flow under any adverse conditions which may develop. Most such prior valves have been operated by fluid pressure from the surface of the earth, and have been constructed in a manner requiring removal of the tubing string from the well in order to permit installation of the safety valve therein.